1. Field of the Invention
The present invention relates to a steering device.
2. Description of Related Art
Hitherto, there has been known a steering device including a column having an outer column and an inner column. See Japanese Patent Application Publication No. 2012-162152 (JP 2012-162152 A). In the steering device, the inner column is relatively movable with respect to the outer column. The inner column is disposed on the upper side with respect to the outer column. The steering device is configured to lock the inner column so that the inner column does not move with respect to the outer column by reducing the diameter of a holding body portion of the outer column by tightening a pair of tightening pieces of the outer column by use of a tightener including a bolt shaft.
Normally, a keylock device is attached to the inner column on the upper side. The keylock device is a device that restricts rotation of a steering member when an ignition key is extracted.
The keylock device includes a protruding portion that advances toward and retracts from the center axis of the steering shaft in response to extraction and insertion of the ignition key. When the protruding portion is inserted into an engagement groove provided in the steering shaft, rotation of the steering shaft is restricted. In addition, as rotation of the steering shaft is restricted, rotation of the steering member connected to an end portion of the steering shaft is also restricted.
When an excessive torque load is applied to the inner column, however, the inner column is rotated to release engagement between the protruding portion and the engagement groove, which may release restriction on rotation of the steering shaft. This may hinder the function of the keylock device, which may result in theft of the vehicle.
In order to prevent such a situation, it is necessary to restrict rotation of the inner column with respect to the outer column. However, carelessly providing a rotation restriction mechanism may hinder contracting operation of the steering column upon a secondary collision, which may adversely affect energy absorption performance upon the secondary collision.